X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fbasic_2%2Frelocation%2Flexs_length.ma;h=2ceec510bb182bd74f6b87bb24ae40094f84e291;hb=c879284b576409cec07e96c1f08510d9d9ac14f3;hp=812a75eeade78d1c2373a6eb7484dc15b212e5f8;hpb=e11ce46390f264e9010157dd36c0b9e71a58ba4b;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs_length.ma b/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs_length.ma
index 812a75eea..2ceec510b 100644
--- a/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs_length.ma
+++ b/matita/matita/contribs/lambdadelta/basic_2/relocation/lexs_length.ma
@@ -19,8 +19,19 @@ include "basic_2/relocation/lexs.ma".
 
 (* Forward lemmas with length for local environments ************************)
 
-(* Basic_2A1: includes: lpx_sn_fwd_length *)
+(* Basic_2A1: uses: lpx_sn_fwd_length *)
 lemma lexs_fwd_length: ∀RN,RP,f,L1,L2. L1 ⪤*[RN, RP, f] L2 → |L1| = |L2|.
 #RM #RP #f #L1 #L2 #H elim H -f -L1 -L2 //
 #f #I1 #I2 #L1 #L2 >length_bind >length_bind //
 qed-.
+
+(* Properties with length for local environments ****************************)
+
+lemma lexs_length_cfull: ∀L1,L2. |L1| = |L2| → ∀f. L1 ⪤*[cfull, cfull, f] L2.
+#L1 elim L1 -L1
+[ #Y2 #H >(length_inv_zero_sn … H) -Y2 //
+| #L1 #I1 #IH #Y2 #H #f
+  elim (length_inv_succ_sn … H) -H #I2 #L2 #HL12 #H destruct
+  elim (pn_split f) * #g #H destruct /3 width=1 by lexs_next, lexs_push/
+]
+qed.